Nonstatic photographic film



Jan. 19 1926. 1,570,078 r E. c. PITMAN NoNsTATIc PHoToGRAPHIc FILM Filed sept. 16, 1920 Patented-Jut '19,- 192s.

1,51o,n1s

lUNITED STATES vPATENT OFFICE,"

EABLE C. PITHAN, 0F PABLIN, NEW JERSEY, ABSIGNOR TO E. I. DUVPO'NT DE mOm 0l' WILMINGTON, DELAWARE, A CORPORATION Ol' DELAWARE.

NONSTATIC PHOTOGBAPHIC FILM,

appiiomon med september is, 1920. semi n. 41am.

To all whom z'tmag/ concern.: c,

Beit known that I, EARLn C. Pri'MaN, a citizen of the United States, and a resident of Parlin, in the county of Middlesex and State of New Jersey, have invented a certain new and useful Nonstatic Photographic Film, of which the following is a specification.

This invention relates to photographic films having provisions for the elimination of discharges of sta-tic electricity. With the .ordinary film these discharges occur whenv the film is stripped from the casting surface, when it is run rapidly through a cinematographic camera and under various other circumstances; Such discharges cause markings on the sensitized emulsion by premature exposure thereof. It is an .object ofthe invention to provide a film which, forypr'actical purposes of manufacture and use, will be free from static ele-ctrlcity, and

it is also an object to ini-prove generally upon films of the character indicated,

For convenience and brevity of description I use the term film .to denote the entire article, whether or not the article includes a sensitized emulsion; the term film body to denote the entire emulsion support whether or not that support is composed of a plurality of layers, sub-films or pellicles; the term backing to denote a layer of a composite film body, which lies adjacentv the other side of the film body from the side intended to directly carry the emulsion;

and I use the term base to denote the portion of a composite film body which 1s 1ntended to carry the backing at one side and the emulsion at the other and to form or include the principle strength-giving portion of the film. On occasion, as will appear from thecontext, I use the term base (or pellicle base) to also indicate the substance, as cellulose acetate 0r cellulose nitrate, which is the primary substance used to form a pellicle.

1n the accom anying drawing I have, without restricting my invention thereto, shown ra film embodying my invention, the

4film body view being aconventional, exaggerated, cross-sectional showing.

According to my invention, I use in the unsaturated. fatty acids (such as sodium sulphoricinoleate), alkali salts of egor albumin, or alkali salts of aromatic sulp'lionic a substance2 or substances, which acids, using the film forming substance either alone or in combination with ahygroscopic substance such as glycerine, the sub-` stances selected forA any specified case to be soluble inthe particular Solvent mixture used for making the pellicle in which the substances are to be incor rated, and such as not to cause precipitation ofthe pellicle base used for the pellicle. The film former acts to convert the isolated drops of moisture, collecting on the film, into a homogeneous film, thereby increasing conductivity. To the best of my knowledge the substances I call film formers, and exemplified by the substances named above, function by virtue yof their common characteristics of having the ability to reduce surface tension. Therefore, lacking a common generic term for such substances, I, for convenience in claiming, make reference in the claims to this ability. It is to be understood, however, that the reference is for convenience, and not by way of limitation, the intent being to include substances, exemplified'by saponin and the like, which have the ability to convert` ultimately appears that that property is other than the ability to reduce surface tension. The hygroscopic substance is advantageous in that it increases conductivity by increasing the moisture content,- the film former 1s, of course, valuable whether or not the hygroscopic substance is used also, as some moisture is present in any case.

In general, and as previousl indicated, a film body, i. e. the entire emu sion support, may consist of one layer only; or may consist of a plurality of layers, one of the layers being the backin and the remainder of the' body being the base or principal strengthiving layer or layers of the film body. Vhen incorporating the various substances, e. g. saponin and glycerine, in accordance with the invention, they may be laced in a film body not comprising a bac ing and made from any desired pellicle base, e. cellulose acetate; or such substances may e, in the first instance, placed in a backing and such backin a phed to any desired base layer. The igiacliing may be one which primarily functions merely by virtue of the substances and, so, may not contain a pelllcle base, e. g. cellulose acetate; or it may contain a pellicle base of any suitable character and either having substantially the same conductivity as the ing the base of the lm, or having a conductivity somewhat greater than that of the pellicle base used in makmg the base of the film and enabling the pellicle base of the backing to itself serve in giving the backing a superior conductivity.

As tothe use for the backing of a pellicle base which is itself of superior conductivity, I may apply a backing layer of carbohydrate ester of relatively low esterication, as regards conductivity (the conductlvity, and the hygroscopicity, increasing as the esterification decreases) e. g. cellulose acetate having 55% or less of combined acetic acid, that is, not over 55% of combined acetic acid, and preferably having about 54%, to a film base of carbohydrate ester of relatively high esterication, as regards conductivity (the conduct-ivity, and the hygroscopicity, decreasing as the esterification increases), e. g. cellulose nitrate having a nitrogen content of more than lll/2%, preferably about 11.8%, to 12%. Experience has shown that, if proper strength is to be secured in a film primarily of cellulose nitrate, then a cellulose nitrate having a nitrogen content of more than lll/2% is a practical necessity despite the fact, that, used alone, it is liable to static discharges due to its nonconductivity. By the present arrangement I provide a primarily cellulose nitrate film which has the strength demanded by the trade and yet is conductive and substantially non-static. As will be understood, a film of the character just indicated may, if desired, contain no added hygroscopic or film- 1plellicle base used in makforming substances and yet present the advantage of conductivity to a marked deree. for the base and the backing solution may be used; conveniently the below-given formulas l, and 2 with the saponin omitted, may be used for the base and the backing, respectively.

lVhile the mentioned backing is highly advantageous of itself, I have. found, as previously indicated, that the incorporation, in such a backing, of conductivity-increasing substances, as a film former, alone or in combination with a hygroscopic substance, gives a particularly satisfactory film.

The mechanical operations of 'naking films in accordance with my-invention will be evident to those skilled in the art, the casting of films, and similar operations, as such, being of course Well known in the art. The backing solution may be a plied, and the solvents evaporated, to give title backing, in any convenient manner. Below I give formulas illustrative of films embodying my invention, it being understood that I do not restrict my invention to the examples given. ln the formulas figures refer to parts by weight.

(2) For a backing containing a film former, saponin, the following formula may be used In making up, to the combined solvents add (a) the saponin and (b) the cellulose acetate, in order.

(3) For a backing containing a film former, saponin, and a hygroscopic substance, glycerine, the formula, as to ingredients, ranges, and preferred amounts, may be -the same as for 2 except that it should in addition include approximately 0.25 to 15 parts, preferably 1 part, of glycerine. When preparing, add (a) the glycerine, the sap0- nin, and (c) the cellulose acetate, in order, to the combined solvents. As indicated previously, and as specifically here exemplified by the glycerine, the hygroscopic substance is In such cases any suitable formulas soluble in the particular solvent mixture used for making the pellicle, and such as not to cause precipitation of the pellicle base.

While the above lbackin s may be of any desired thickness serving t e ends sou ht, I`

have found a relatively thin backingA esir-` able. A film base for them may be according to formula 1.

In the above backing formulas the cellulose acetate ma have 55% or less of comused for the backings and that such bacliings be applied to a film base of cellulosenitratehaving a nitrogen content of over lll/2%.

To provide backings which are soluble in water and can be totally removed, say in development (after which there is no longer any danger from static marks), saponin and glycerine in the preferred amounts and ranges iven in formulas 2 and 3 may be disso ved in 100 to 400, preferably 200, parts of denatured alcohol.

. Although for purposes of specific illustration, I have made more particular reference to cellulose acetate as the pellicle base to be used for the backing, it is to be understood that I do not restrict my invention to the use of cellulose acetate as various other materials, more particularly, othei carbohydrate esters, can be used for the ellicle containing the film former, alone or in combination with a hygroscopic substance.

As previously stated, the conductivity-in-l creasing substance may be incorporated in a film body not having a backing. For .example, theymay be incorporated in a pellicle of cellulose nitrate, preferably having over lll/2% nitrogen content. Thus:-

(4) For a pellicle containing a film former, saponin, the formula as to 1ngredients, ranges and preferred amounts,

may be the saine as 1 except that it should in addition include 0.0125 to 0.3, preferably 0.05 part of saponin. In preparing, add (a) the saponin and (5) the cellulose nitrate in order to the combined solvents; and

(5) For a pellicle containing a film former, saponin, and an hygroscopic substance, glycerine, formula 4 may be used, using in additionv 0.5 to 10, preferably 2,

parts of glycerine; To prepare. add (a.) the glycerine, (b) the saponin, and (c) the cellulose nitrate in order, to the combined solvents.

`While, in describing mv .inven tion, I have referred to it as embodied `in a body Without a backing and as embodied in a backing it is to be understood that by neither of these terms do -I exclude vfilms wherein the pellicle which more particularly exemplifies the invention may have applied to its (normally) exposed surface a coatin of such character as not to destroy the e cacy of 'the pellicle, the pellicle from the standpoint of the present invention, yet being without a backing or being a backing as the case may be. Although I have referred more particularly to a cellulose 'acetate backinflr on a cellulose nitrate base, it is to be understood that I may if desired apply a backin of c ellulose nitrate ofl relatively low esteri cation, as regards conductivity, e. g. cellulose nitrate having a nitrogen content of not over lll/2%, that is 111/% or less and preferably 10.9%, and containing or not containing added conductivity-increasing substances, to a base 'of cellulose acetate of relatively high esterification, as regards conductivity, e. g.

strength, conductivity and hygroscopicity.

Of course, should it be desired for any reason, both the film base and the backing of a backed film may contain the conductivity-increasing substances. I claim 1. A photographic film containing a substance capable of reducing surface tension.

2. photographic film saponin.

3. photographic film containing a nonprecipitating hygroscopic substance and a substance capable of reducing surface tension.

4. A photographic film containing glycerine and a substance capable of reducing surface tension.

5. photographic film containing a nonprecipitating hygroscopic substance and saponin.

6. A photographic film containing glycerme and saponin.

7. A photographic film having a base and a. backing, said backing comprising 4 to 16 parts of a pellicle base and 0.005 to 0.2 parts of saponin.

8. A photographic film having a base and a backing, said backing comprising .6 parts of a pellicle base and 0.02 part of saponin.

9. A photogra4 hic film having a base and a backing, said acking comprising 4 to 16 containing arts of a pellicle base, a nonprecipitating ygroscopic substance, and 0.005 to 0.2 part of saponin.

10. A photographic having a base and abackin said backing comlirrsmg 6 arts of a pel icle base, a non-precipitatin` Eygroseopic substance, and 0.02 part o saponin.

11. A photographic film having a base and a backing said backing comprislng 4 to 16 parts of a pellicle base, 0.25 to 15 parts of glycerine, and a substance capable of reducin surface tension.

12. A p otographic film having a base and a backing, lsaid backing comprising 6 parts of a pellicle base, 1 art of glycerine, and a substance -capable o reducing surface tension.

13. A photographic film-having a base and a backing, said backlng comprising 4 to 16 parts of a pellicle base, 0.25 to 15 parts of glycerine, and 0.005 to 0.2 part of saponin. Y

14. A photographic film having a base and a backing, said backing comprising 6 parts of a pell'cle base, 1v part of glycerme, and 0.02 part of saponln.

15. A photographic film having a base of cellulose ester and a backing of a difierent cellulose ester than that of the base, the ester of said backing being of greater conductivity than that of the base..

16. A photographic film having a base of cellulose ester and a backing of a different cellulose ester than that of the base, the ester of said backing being of l greater hygrosco icity than that of the base.

17. photographic film having a base of cellulose ester, and a backing of a different cellulose ester than that of the base, the esterification of said backingbemg relatlvely lower, as regards conductivity, than the esterification of said base.

18. A photographic film having a base element and a backing` element, one of said elements being of cellulose nitrate and the other of cellulose acetate, the cellulose ester of said backing element being of greater conductivity than that of said base element.

19. A photographic film having a base of cellulose nitrate and a backing of cellulose acetate, the cellulose acetate of said backing being of greater conductivity than the cellu- .lose nitrate of said base.

22. A photogra hic film having a base of cellulose ester an a backing of a different cellulose ester thanthat of the base, the ester of said backing being of greater conductivity than that of the base, and said backinA containing /a conductivity-increasing su stance.

23. A photographic film having a base of cellulose nitrate and a backing of cellulose acetate, the cellulose nitrate having a nitrogen content of over 11i/2% and the cellulose acetate having not over 55% combined acetic acid, and said backing containing 4 to 16 parts of cellulose acetate, and 0.005 to 0.2 part of sa onin.

24. A p otographic film having a base ofj cellulose nitrate and .a backing of cellulose acetate, the cellulose nitrate having a nitrogen content of over lll/2% and the cellulose acetate having not over 55% combined acetic acid, and said backin containing 6 parts of cellulose acetate, an 0.02 part of saponin.

25. A photographic film having a base ofY cellulose nitrate and a backing of cellulose acetate, the cellulose nitrate having a nitrogen content of over 111/% and the cellulose acetate having not over 55% combined acet- 1c acid, and said backing containing 4 to 16 Parts of cellulose acetate, a non-precipitatmg hygroscopic substance, and 0.005 to 0.2 part of saponin.

26. A photographic film having a base of cellulose nitrate and a backing of cellulose acetate, the cellulose nitrate having a ntrogen content of over lll/2% and the cellulose acetate having not over 55% combined acetic acid, and said backing containing 6 parts of cellulose acetate, a non-precipitatmg hygroscopic substance, and 0.02 part of saponm.

27. A photographic film having a base of cellulose nitrate and a backing of cellulose acetate, the cellulose nitrate having a nitrogen content of over 111/% and the cellulose acetate having not over 55% combined acetic acid, and said backing containing 4 to 16 parts of cellulose acetate, 0.25 to 15 parts of glycerine, and a substance capable of reducin surface tension. y

28. A p otographic lm having a base of cellulose nitrate and a backing of cellulose acetate, the cellulose nitrate having a nitrogen content of over lll/2% and the cellulose acetate having not over 55% combined acetic acid, and said backing containing 6 parts of cellulose acetate, 1 part of glycerine, and a substance capable of reducing surface tension.

29. A photographic film having a base of cellulose nitrate and a backing of cellulose parts of cellulose acetate, 0.25 to 15 parts of acetic acid, and said backing containing 6 glycerne, and 0.005 to 0.2, part of suponin. arts of cellulose acetate, l part of glycer- 30. A photographic lm having a base of me, and 0.02 part of saponin. 10 cellulose nitrate and s, backing of cellulose In testimony whereof I affix my Signa- 5 acetate, the cellulose nitrate having a nitroture.

gen content of over lll/2% and the cellul lose acetate having not over 55% combined EARLE C. PITMAN. 

